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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Focus Session: Soft Matter and Nanocomposites: New Opportunities with Advanced Neutron Sources 1
CPP 33.1: Hauptvortrag
Donnerstag, 8. September 2022, 09:30–10:00, H38
Cooperative and non-Gaussian dynamics of entanglement strands in polymer melts — •Margarita Kruteva1, Michaela Zamponi2, Ingo Hoffmann3, Jürgen Allgaier1, Lutz Willner1, Andreas Wischnewski1, Michael Monkenbusch1, and Dieter Richter1 — 1Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS-1: Neutron Scattering and Biological Matter), 52425 Jülich, Germany — 2Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany — 3Institut Laue-Langevin (ILL), B.P. 156, F-38042 Grenoble Cedex 9, France
We report neutron spin echo investigations on the motion of short tracer chains in highly entangled melts [1,2]. The tracers were found to undergo sub-diffusion behavior. Unexpectedly the sub-diffusion is limited by a distance very close to the tube diameter of the respective highly entangled host. The cross-over distance to Fickian diffusion, thereby, is independent of the tracer’s length. The Fickian diffusivity agreed with the macroscopic results. We found that the Rouse dynamics of the tracers is strongly non-Gaussian with a related segment displacement distribution narrower than the Gaussian counterpart. These results were understood as a consequence of highly cooperative motion of the tracers with the host that mirrors the host dynamics within the tube. The phenomena were found both in a polyolefin (polyethylene) as well as in a polyether (polyethylene-oxide) indicating their generality. (1) Zamponi, M. et al. Phys. Rev. Lett. 2021, 126 (18), 187801. (2) Kruteva, M. et al. Macromolecules 2021, accepted.